[davidbliss]

Someone may have at sometime adjusted wrongly the valve clearance by grinding to much off the stem of the valve, this stops the very crude rubbish compression release from working, it consists of small bump on the back of the cam. Seen this done to worn out engines to get better running they do idle better but at a cost to your fingers being stretch if its not done aggressively to get the engine to turn over. and a loose blade causes same issues as there is then little inertia help given from the blade. ignition points opening rather early is another cause, expect its one with short peg that rubs on the crank, measure the clearance under the peg to points arm, just increase the clearance a little and then check the points actually open as it a bit of a juggling act as sometimes with block and peg wear.

[davidbliss]

Going back the 23 years got good backup and sensible helps to a problem, and looks like the new engine might have had known ignition issues and the firm should I would have thought known this and sorted it, and fist engine also had carburettor issues especially at idle, new ones have fixed air bypass adjustments? where as the old were adjustable. The carburettor was changed on the first return and it did run much better at idle but was still running rich at half to three quarter throttle openings on light load however not right. and ran at full speed made a lots of hot air and with loud exhaust note. I was sent a comparison chart why as not of the early 2001 engine to compare they said new engines ran cooler to what, well the old engine doesn’t even get in a sweat and quieter in comparison also very miserly in fuel consumption. So have had this before to save the Planet we seem to make engines to use more fuel to generate heat. We did a side by side test, engines were shown to be cold, started and allowed to warm, temperature shown, both then ran flat out, that showed a huge difference in exhaust temperatures and looking at the plugs of the new one and its doing the same as must have been very hot indeed.

• This reply was modified 3 weeks, 2 days ago by davidbliss.
• This reply was modified 3 weeks, 2 days ago by davidbliss. Reason: spelling
• This reply was modified 3 weeks, 2 days ago by davidbliss. Reason: corrected wrong word

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[davidbliss]

Forgot to attach the bit of info on electronic ignition I was sent this.

David
Here’s a write up on how the Briggs electronic coils work to advance the timing at higher rpms. I suspect your coil on the weak side is out of spec.

“The simple, but very effective, spark control system advances the ignition timing, causing the plug to fire earlier (in degrees of crank rotation) as RPMs go up. The faster you spin the magnet on the flywheel past the trigger and primary windings in the coil, the greater the potential voltage that is developed. Since it only takes about 1.0 volts from the trigger coil to turn the Darlington control transistor on (and off), the faster (in terms of crank rotation degrees) the potential builds to the required 1.0 volts, the earlier the induced current in the primary side of the coil will begin to build. And likewise, the earlier the trigger coil potential reaches the 1.0 volts and fires the plug.”

A standard inductive timing light might tell the story here.

[davidbliss]

This is if any one is thinking of updating something with one of the Briggs & Stratton V twin Vanguard as have had over a year in getting one of those engines to run nearly as it should. I have one of the first now 23 year old V twin Vanguard Briggs that still runs as new and was made in Japan and few people know that, to start with the old engine seems to run on fumes and never seems to get hot, where as the new engine uses more petrol and gets very hot to such a extent it made a pretty good bird scarier if turned off. With my years of tune ears and observations said it was a Wrong’un. Symptoms were, engine oil got black black instantly and was drained by me and by them as smelt of petrol, loud harsh exhaust sound and got very hot almost instantly if ran flat out. Then if run at half to three quarter throttle sooted the left one plug with other burnt white if worked hard, If idled only short times would soot it left plug and on a cold start up would cause spitting until hot. So the a bit of a slog to get anywhere started, I got couldn’t find anything wrong and runs within PARAMETERS? and that to me says anything goes. Well engine been back twice, I think if had got it off the scrap heap would have sorted it myself, just before it went back second time again I did a simple test of removing a plug lead and fitted a spare plug so not to cause damage to ignition coil and ran it at half throttle this showed left cylinder played with the loss of the right cylinder and doing the same reversed the right cylinder was working hard, and just got some info from the US might have been the cause of cylinder difference but not the fuelling. Three weeks ago was sent a New engine, and isn’t a quick fix as has to be stripped of bits not required and built up with dual shaft drive and heat shield and back in the mower took 8hrs. Now I am not impressed the new engine is the complete opposite in that it runs very weak but is usable and with short runs isn’t going to cause issues. This is what was sent from the US, and what I say pluggs tells all, what do people think. photos of plugs the last ones I have never seen plugs burnt that clean or pink but there we will see.

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[davidbliss]

Poulan Sweden? however brain leaked but I have an idea they made chainsaws.

[davidbliss]

I must have had several over the years, they’re a absolute nightmare being temperamental they altered them I reckon hourly so very difficult to find interchangeable parts if not complete, Its a funny feeling working on those that had been in service, one had the barrel bent so was tight to turn over, being all alloy I was surprised it hadn’t broken, mostly little was usable. The one I got going was complete in the end, I only had one usable barrel even this one had shrapnel damage, a sliver had gone through the cover and sliced a 5 mm slot in a fin curling it up like a pigs tail without bending or braking the fin, just unbelievable of how, they did make a twin cylinder version, was told you could weld with one of those.

[davidbliss]

Homelite were used on many generators to chainsaws, Drones and Ken Wallis them in his Auto-Gyro, one that was used during the war used for the emergency generator that sat under wireless operators desk? in the liberator was bit unusual being two stroke with a governed rotary inlet valve, A 8-1 pet-oil mix and a no float carburettor sat on-top of the tank with hand petrol pump to start, then used sort of petrol lift by bubbling air into a pipe that was submerged in the petrol tank. They had to run on 100 octane and with extreme cold had the masked type of plug-ignition, running at low altitude combustion chamber would soon overheat and stop. were very problematic to start if not done properly, one I built up for a museum had been given a Latin name by one of the air crew of scratched into the top of Sh-ttus-Rotus. Most likely all written archive is now lost thats a bit sad and I just remembered it was a Mr Alfred Feaviour got some recognition for development of improvements for the masked plug ignition for the first WW1 aircraft engines, I have them from 1906 it was used and plug savers still sold in the fifties. Photos, the Homelite carb and petrol lift. left to right, 1906 6 HP Rover, Homelite WW 2 gennerator, 1950s plug saver.

• This reply was modified 1 month, 2 weeks ago by davidbliss.

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[davidbliss]

I suppose going back many years just took it for granted some engines although looked the same but weren’t and a real pain to work on, Aspera made light duty engines without the needle roller big and little end bearings and industrial with, Teles used them on there chainsaws, I had one brought to me that was running a bit under powered and flat as had so many, took the exhaust gauze out and it made a huge difference, as only had a few screws holding the complete exhaust on took it off to look at the exhaust ports, they looked like never been run, turning the engine over to look at the piston that again looked new, just noticed bottom of piston skirt went above bottom of the exhaust ports so was sucking back in exhaust gasses, well have a idea fitted barrel and piston off a scrapper Fly-mow,as had a wight coloured barrel on a blue saw but where did the odd ball piston a barrel come off or balls up of manufacture, the bit interesting was the scrapper piston skirt was longer and shaped to cover the exhaust ports. It didn’t sound much different but seemed to have twice the torque. The JLO engines were just longer lived often neglected but kept going.

[davidbliss]

Unless its worn out every where else its worth repairing, the pump would not be worked by the big end dibber, would have thought off the camshaft, I get really cheesed off with peoples attitude nowadays, many new things you take them out of the packaging use a few times and they’re scrap. Yesterday helping my daughter took my three chain saws all old thirty – forty years old plus but good quality all had been scrapped because of minor carburettor issues and other things fixed and never had one give trouble since, after taking down a large Chestnut tree in November that was easy, I chickened out for one smaller rotten overhanging one with bad knees and having to work part off a ladder got the professionals that soon had it down, like me they had chainsaws from small to large but not as old, talking to them about the chain saws they said had two fairly new saws all dead with issues because of electronics controlling fuelling, WHY as a good quality carb will give years of trouble free use. Today to be green engines seem to be made to use more fuel and fail with electronic issues, for over a year had issues with a new V twin Briggs & Stratton, supposedly emission complaint it drinks petrol, soots one plug and burns the other white and has now gone back twice, Idiots says it runs within Parameters? so I have been having same issues with inability of people to fix a simple thing. Going west got feed back to say with the coils having auto advance electronic advance one coil must have had a fault.

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[davidbliss]

Engine sort of sounds ok apart from the spitting back that’s not quite like an ignition type fault sound causing the spitting, I have had early veteran car engines do something similar as the inlet valves are atmospherically opened and not mechanical, you have to get the valve spring strength fine tuned, to strong and you loose power and to weak they can sort of give a double skip bounce and spit at a particular throttle opening, and a sticking valve or broken valve spring can also causes same symptoms, I did have a valve insert start to drop out on a alloy head, it didn’t spit but just like a intermittent ignition fault causing shorted ignition. I have just had a thought valve timing, if the engine sparks at every top dead centre what I call a lazy spark if the inlet is opening early and exhaust is closing late they can spit back so check valve clearances are correct and are rocking at pistons dead top centre.

[davidbliss]

I have been restoring engines in size from small to large, the older bronze carbs are slightly easier as can heat parts but the die-cast monkey metal ones can be very delicate and more care is needed to get stubborn screws and jets out, many years ago just by accident after washing my hands left a real badly petrol varnish encrusted carburettor in the washing bowl full of hot soapy water, just thinking it might help clean some of the rubbish off the outside. Well it made a tremendous difference most of the brown varnish like deposits left by the petrol had gone whitish and blew away with the air line, even some of the jets just unscrewed easily, so out with a saucepan added a table spoon of washing powder and boiled it for several minutes and left it soaking overnight it was like magic, even managed to clear those very very small cross drillings into the Venturi that some small product carbs have, I had one carburettor brought to me looking like new but wouldn’t idle, I just guessed a long drilling might be blocked, bit of WD 40 or washing up liquid over one end and bit of air in the other and no bubbles and boiling it worked as so easy. Now a word of warning, a DO NOT DO and many people would have said and seen this coming, I would often put a float into hot water to find pin-hole leaks as hot air expands, solder up hole, if it hadn’t got one its important to drill a very small hole and let the float cool and then solder that up and check again. This particular time water must have been near to boiling and just dropped it in and poked it under, I had not checked carefully enough as must have had some bit of petrol in and a minutest hole as instantly it went off pop and took some time teasing it back into shape. Just recently started to rebuild a very early Zenith as jets were so badly damaged had to mill part of them away and make new with screw cut threads as a odd (French?)pitch, one blanking plug had less than three threads. As for good idling I like Zenith and fit those, and can still can get some new, like the 24 T that fitted tractors, Villiers and Petters even the little J.A.P water pumps we still have two in use from the 40s and replaced the old carbs with new 40 odd years ago 13 T CA-2 identical but now I find the petrol pipes are push on. Meetings in London still had parts for the J.A.P and Villiers.

• This reply was modified 3 months, 2 weeks ago by davidbliss.

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[davidbliss]

I can see why the O rings are not a fix and forget as taps wear in use and wouldn’t accommodate the wear. If the taps are not fully on or off the O ring is allowed to expand and if then pushed fully home it can cut a bits out of the O ring, it all so happens to the modern ball valves if not turned fully on or off and left. Whats wrong with keeping them wet with fuel, I still have original tanks in as new condition and began life and used for over 100 years, found the two-strokes gave less trouble so the oil must have helped and often tap parts could be screwed up to expand the corks, where the later taps were fixed and throw away, I have laid up some for nearly forty years all I did then was do a 50-50 mix of oil and lamp oil paraffin spraying it in and left, if not too late it even seems to keep the die-cast carburettor parts in better order as any jets can be very difficult to remove after sitting dry for many years and the metal corrodes and expands.

[davidbliss]

Carb looks early and tank looks a late type, they spanned many years.

[davidbliss]

That flywheel is die cast, can all ready see one fan blade broken off, mostly the wico flywheel has cast in a centre steel insert, and shafts are normally parallel, mostly there are three threaded holes near the centre for draw bolts and if so just be careful not to screw any set screws through to far to catch the coil, if the alloy crankcase is cracked just weld it if its the flywheel its shot as its monkey metal and a definitely do not put puller legs on the outer rim as can break like glass with age.

[davidbliss]

I have come up against all-sorts of barriers trying to get replacement parts for old machinery. often people are not interested its a one off so not worth there while, however there are ways of finding things just think out of the box, I have seen cam timing belts used turned upside down, they are very strong, I use them for making strap wrenches, allot better use than in there proper use if they break. Four years ago wanted a replacement for the leather always stretching belt on my car, so equipped with the length off to the power transmission supplier, we haven’t got anything that size but can get it made, we’ll get get back to you with a price, that came back at £60 plus vat for a Gates belt. We ran an old 40 plus year old Cat for work and going west could get spares people were very helpful, so did the same for the belt. I wondered what the T Ford used and found they used from a 23inch in ten steps to a 36 inch and I needed a 30+ one and at only £3-00 for the shortest to the longest costing only £5-50 so a bit of a gamble and had two sent this cost I think less than £15 including post for the two Gates belts from the US, getting stuff sent isn’t as easy today as some things have to go through a re-shipper so adds a bit.

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[Author]

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